This invention relates to alternate reverse or so-called SZ-twisting.
More specifically, the object of the present invention is to provide an alternate reverse twisting method to form a product, such as a cable or similar, composed of an inner core element (9) and/or of alternately reversely twisted elongated elements (2) which can be wires, leads, optical fibers or their groups, or similar or which can be twisted as quads of wires, leads etc., by an alternate reverse twisting apparatus comprising:
a fixed dividing means (3) at the input end of the elements (2,9) to be treated, PA1 to opposite directions periodically rotating twisting means (6) at the output end of the treated elements (2,9), PA1 thereafter arranging pressing means (7), preferably a nipple, for pressing the treated elements (2,9) tightly against each other, and PA1 means (4,5) for defining feedpaths for the elements (2,9) to be treated, which means are arranged between said dividing and twisting means. PA1 a fixed dividing means (3) at a first station forming the input end of the elements (2,9) to be treated at the upstream end of the apparatus, PA1 at a second station periodically rotating twisting means (6) at the output end of the treated elements (2,9) between the upstream and downstream ends, PA1 at a third station pressing means (7), preferably a nipple, provided for pressing said treated elements (2,9) tightly against each other at the downstream end and PA1 means (4,5) for defining feedpaths of said elements (2,9) to be treated, which means are arranged between said dividing and twisting means (3,6).
The object of the present invention is also to provide an alternate reverse twisting apparatus to form a product, such as a cable or similar, composed of an inner core element (9) and/or alternately reversely twisted elongated elements (2) which can be wires, leads, optical fibers or their groups or similar or which can be twisted as quads of wires, leads etc. The apparatus comprises different treatment stations from an upstream to a downstream end, as follows:
Further the object of the present invention is the provision of an alternate reversely twisted product, such as an electric and/or optical cable, lead or similar elements.
Elongated elements as leads, wires or similar are conventionally produced in a SZ-twisting apparatus for example by means of a tracked pulling device from input sides for pulling the elongated elements through a first circumferentially perforated holeplate serving as a fixed dividing means and then through to an to an opposite directions by means of a periodically rotating second circumferentially perforated oscillating holeplate for serving as a twisting means and thereafter pulling the elongated elements into a pressing means, preferably a nipple, in which the elements are pressed tightly against each other. Further a spinning device can be used to bind the pressed elements as an alternate reversely twisted product. After completion of the stages using the pulling device, spooling either takes place or the twisted product can be fed to a next work phase. In this kind of a conventional SZ-twisting device it has usually been placed between the dividing and twisting means so that a tubular intermediate element rotating with the twisting means can be centrally fixed to it as well as mounted at its opposite end in bearings to rotate in relation to the dividing means.
This kind of a conventional arrangement includes, however, the disadvantage, that the rotation speed of the intermediate element is always constant, so that twisting turns of elongated elements tends to accumulate to the end towards the twisting means, whereby the pitch of the elongated elements becomes denser and their angular deviation into the twisting means increases. Then between the direction reverse points of the twisting direction the number of helices of the twisted elements is very limited being 10 at the highest, and also the force required for pulling the elements increases whereby the helices of the twisted product tends to open.
This main problem, i.e., an accumulation of the elements to be twisted, a large pulling force and a low number of helices has previously been tried to solve the problems by principally three different methods, however, without finding a satisfactory solution.
Firstly, according to patent publication U.S. Pat. No. 3,910,022 and U.S. Pat. No. 4,414,802 between a fixed dividing holeplate at one end and, at another end downstream of the other end, there is provided a periodically oscillating twisting holeplate for rotating in different directions, and a torsion-elastic torsion pipe is provided wherein the inner space is divided by spacers for keeping the elements to be twisted apart from each other, so that the spacers thus define feedpaths of individual elements to be twisted.
Secondly, according to published FI-patent application No. 803958 and U.S. Pat. No. 4,426,838 between a fixed dividing holeplate and periodically oscillating twisting holeplate which oscillate in opposite directions, there is a torsion-elastic torsion cable, rod or wire, to which several disk-shaped and circumferentially perforated disks are fixed and spaced apart in axial direction, whereby the opening of the perforated disks serve as guide means for individual elements to be twisted.
Thirdly, according to U.S. Pat. No. 4,426,839 and SU Publication No. 546,943 between the fixed dividing holeplate and a periodically oscillating twisting holeplate oscillating in opposite directions there are several separate pipe or spiral means, so that the space inside each individual pipe or spiral means serves as a guide means for individual elements to be twisted. According to said U.S. Pat. No. 4,426,839 the pipe means have been bound together by plates provided with circumferential openings for the pipe means, while according to the SU-publication the spiral means extend freely between dividing and twisting means.
The above-mentioned disadvantage, i.e. accumulation of elements, having a great pulling force, low number of helics and a so-called "skip-rope" phenomonen occuring especially at high rotating speeds a solution has also been tried to solve the problem according to the teachings of U.S. Pat. No. 3,847,190, in which the pipes defining feed-paths of individual elongated elements to be twisted have been arranged inside a larger cylindrical mantle tube and fixed at one of their ends to a fixed dividing holeplate and at their other ends they are fixed to the end flange of said rotating mantle tube. Disadvantages have also been encountered when trying to solve the problem by using the apparatus according to DE-publication No. 3404264 which is an improved conventional SZ-starnding apparatus which include one rigid central pipe rotating with the twisting means whereby elements to be twisted are wound around the periphery of said central pipe. Attempts have been made to solve the jamming effect problem by accumulation by providing the dividing holeplate with its own rotation drive and by mounting an intermediate circumferentially perforated holeplate in bearings onto the periphery of the central pipe and providing it with its own rotation drive. Thus the axial distance by which the elongated elements are wound around the central pipe can be increased somewhat due to the intermediate plate, but the main problem, i.e. growing friction and low number of helices cannot yet be eliminated.
Though it has been possible by the afore-mentioned solutions to slightly reduce the accumulation tendency of the elements to be twisted as well as the adverse effects of this disadvantage the goal has not yet been achieved in a satisfactory manner. Some of the most substantial disadvantages are set forth below.
When a torsion-elastic pipe, inside of which the elongated elements to be twisted pass, is used between the dividing and twisting means the limited twisting ability of the torsion pipe restricts twisting turns of the pipe and thus also twisting turns of the elements to be twisted, whereby the reverse points in the twisting direction must be placed remarkably close to each other, which is disadvantageous.
When a torsion cable or similar is used between the dividing and twisting means and when said torsion cable is provided with several axially spaced apart perforated disks to guide individual elongated elements, said elongated elements are wound against said torsion cable. Thus it is impossible to eliminate the very remarkable disadvantages, i.e. jamming factor and growing friction when the number of twisting turns in one direction increase over 10. Further can be mentioned that it is impossible to produce by this kind of method or apparatus products requiring the use of a central or "core" element.
When parallel and annularly adapted means, i.e. spirals or pipes, for defining the feedpaths for individual elongated elements are used between the dividing and twisting means it is not possible to apply high rotational speeds for twisting, but because of sag and centrifugal force said means for defining the feedpaths of elements strive to detach and also easily twist unevenly in relation to each other, which significantly impedes easy twisting and increases the probability for producing a cable unfit for its purpose.